The right thalamus may play an important role in anesthesia-awakening regulation in frogs

Dynamics of electroencephalogram oscillations underlie right-eye preferences in predatory behavior of the music frog

Visual lateralization is a typical characteristic of many vertebrates; however, its underlying dynamic neural mechanism is unclear. In this study, predatory responses and dynamic brain activities were evaluated in the Emei music frog (Nidirana daunchina) to assess the potential eye preferences and their underlying dynamic neural mechanism, using behavioral and electrophysiological experiments, respectively. To do this, when the prey stimulus (live cricket and leaf as control) was moved around the frogs in both clockwise and anticlockwise directions at constant velocity, the number of predatory responses were counted and electroencephalogram (EEG) absolute power spectra for each band were measured for the telencephalon, diencephalon and mesencephalon. The results showed that: (1) no significant differences in the number of predatory responses could be found for the control (leaf), but the number of predatory responses for the right visual field (RVF) was significantly greater than that for the left visual field (LVF) when the live cricket was moved into the RVF clockwise; (2) compared with no stimulus in the visual field and stimulus in the LVF, the power spectra of each EEG band were greater when the prey stimulus was moved into the RVF clockwise; and (3) the power spectra of the theta, alpha and beta bands in the left diencephalon were significantly greater than those of the right counterpart for the clockwise direction, but similar significant differences presented for the delta, theta and alpha bands in the anticlockwise direction. Together, the results suggested that right-eye preferences for predatory behaviors exist in music frogs, and that the dynamics of EEG oscillations might underlie this right eye/left hemisphere advantage.

Preference of spectral features in auditory processing for advertisement calls in the music frogs

BACKGROUND

Animal vocal signals encode very important information for communication during which the importance of temporal and spectral characteristics of vocalizations is always asymmetrical and species-specific. However, it is still unknown how auditory system represents this asymmetrical and species-specific patterns. In this study, auditory event related potential (ERP) changes were evaluated in the Emei music frog (Babina daunchina) to assess the differences in eliciting neural responses of both temporal and spectral features for the telencephalon, diencephalon and mesencephalon respectively. To do this, an acoustic playback experiment using an oddball paradigm design was conducted, in which an original advertisement call (OC), its spectral feature preserved version (SC) and temporal feature preserved version (TC) were used as deviant stimuli with synthesized white noise as standard stimulus.

RESULTS

The present results show that 1) compared with TC, more similar ERP components were evoked by OC and SC; and 2) the P3a amplitudes in the forebrain evoked by OC were significantly higher in males than in females.

CONCLUSIONS

Together, the results provide evidence for suggesting neural processing for conspecific vocalization may prefer to the spectral features in the music frog, prompting speculation that the spectral features may play more important roles in auditory object perception or vocal communication in this species. In addition, the neural processing for auditory perception is sexually dimorphic.

Auditory perception exhibits sexual dimorphism and left telencephalic dominance in Xenopus laevis

Sex differences in both vocalization and auditory processing have been commonly found in vocal animals, although the underlying neural mechanisms associated with sexual dimorphism of auditory processing are not well understood. In this study we investigated whether auditory perception exhibits sexual dimorphism in Xenopus laevis. To do this we measured event-related potentials (ERPs) evoked by white noise (WN) and conspecific calls in the telencephalon, diencephalon and mesencephalon respectively. Results showed that (1) the N1 amplitudes evoked in the right telencephalon and right diencephalon of males by WN are significantly different from those evoked in females; (2) in males the N1 amplitudes evoked by conspecific calls are significantly different from those evoked by WN; (3) in females the N1 amplitude for the left mesencephalon was significantly lower than for other brain areas, while the P2 and P3 amplitudes for the right mesencephalon were the smallest; in contrast these amplitudes for the left mesencephalon were the smallest in males. These results suggest auditory perception is sexually dimorphic. Moreover, the amplitude of each ERP component (N1, P2 and P3) for the left telencephalon was the largest in females and/or males, suggesting that left telencephalic dominance exists for auditory perception in Xenopus.

Summary: Investigation of auditory neural mechanisms in the South African clawed frog (Xenopus laevis) indicates that auditory perception exhibits sexual dimorphism and left telencephalic advantage.